JPH0536563B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a stair block for seawalls used on the coast.

<Prior art> In order to facilitate activities such as playing near the water, fishing, and getting on and off boats, some seawalls are formed in the form of steps, and concrete blocks of various shapes are used for this purpose. things are on the market. In addition to those designed to engage with adjacent blocks, there are also types in which a window is drilled from the top surface to the bottom surface for filling with gravel when the block is installed.

<Problems to be Solved by the Invention> Although a step-shaped seawall with a gentle slope reflects less waves than a seawall with a vertical or steep slope, it has the problem of waves running up the stairs. Therefore, flooding of the ground behind the seawall cannot be prevented unless the seawall and the ground behind it are built high, or a breakwater is installed at the top of the seawall, but building the seawall and the ground behind it high requires construction costs. The construction of a breakwater wall not only spoils the scenery but also makes it inconvenient for people to travel between the hinterland and the waterfront.

This invention aims to realize a block that can construct a step-like seawall with a gentle slope but with less run-up of waves.

<Means for Solving the Problems> The revetment block of the present invention consists of a front part exposed to the outside world and a rear part hidden under the upper revetment block. The upper surface of the front part has a gentle downward slope of about 4° to 8° toward the front, and has a deep recess at a position adjacent to the rear part. And the front end surface is 30°~
It forms a reverse slope of 60 degrees, and a plurality of water guide holes are drilled from this hole toward the above-mentioned recess.

If necessary, a tenon is provided on one of the lower surface of the front portion and the upper surface of the rear portion, and a mortise or tenon groove of a complementary shape to the tenon is provided on the other side.

<Function> The above-mentioned revetment block overlaps the front part of the upper revetment block on its rear part, and the overall slope is 15° to 15°.
Build a seawall by stacking them in a stair-like manner so that the angle is 30°. At this time, the tenon engages with the mortise or tenon between the lower surface of the upper block and the upper surface of the lower block.

The entire seawall constructed in this way is shaped like steps with a gentle slope, allowing people to easily descend to the water's edge.

The incoming waves are effectively received into the water guide hole due to the reverse slope of the front end face of each block.
The reflection of waves and the scattering of droplets on the front end face are suppressed,
The kinetic energy of the wave that enters the water guide hole is absorbed. In this way, since each block sequentially steals the energy of the incoming waves, waves running up the seawall surface are suppressed. Therefore, the height of the top layer of the seawall can be kept to the same level as the ground behind it.

In addition, the gentle slope of 4° to 8° on the top of each block, combined with the fact that there is little splashing of waves at the front of each block, prevents water from forming on the top of each block, reducing the risk of people slipping. It can be reduced.

<Embodiment> In FIG. 1, a seawall block 1 is composed of a front part 2 and a rear part 3. The top surface 4 of the front part 2 is 1/10
(approximately 6 degrees), and has recesses 5, 5 formed at the rearmost part thereof. The front end surface 6 has a reverse slope of 45 degrees, and water guide holes 7, 7, . . . are bored from the front end surface toward the recesses 5, 5.

Figure 2 shows a seawall constructed using the above-mentioned seawall block 1. Foundation 1 with a trapezoidal cross section built on the ocean floor 11
2, there is an upright block 13 with an L-shaped cross section.
is placed, stone gravel 15 is placed behind the upright wall 14, and the front part of the upper surface of the stone gravel 15 is covered with a concrete layer 1.
Covered by 6. The first stage revetment block 1A is placed across the top surface of the concrete layer 16 and the stone gravel 15, and the second to Nth stage revetment blocks 1B are placed on top of it.
~1N shifts its position backward one after another and the total becomes 1/
3 (approximately 20 degrees). 1
Reference numeral 7 indicates a layer of earth and sand constituting the land, and reference numeral 18 represents a stone and gravel layer interposed between the slope of the earth and sand layer 17 and the back of the seawall blocks 1A to 1N.

In the above embodiment, MSL indicates the average water level, and HWL and LWL indicate the high tide water level and the low tide water level, respectively. The top of the upright block 13 is
It is located at a depth of 2.4 m below the standard water surface, and has an upright block 1.
The height of the upright wall 14 of No. 3 is 3 m. The height of each of the seawall blocks 1A to 1N is 0.57 m.
Therefore, the average water level is the 5th stage seawall block 1E.
It is located at a height of 12 cm from the bottom. In addition, when the seawall blocks are stacked in 13 layers as shown in the figure, the average water level is
The height h from MSL to the top of the seawall is 5.01m.

A 1/15 scale model of the above-mentioned seawall was made, the water surface was placed at the height of the average water surface MSL, and the reflectance when waves corresponding to wave heights of 1 m and 2 m were applied was determined by line 3 in Figure 3.
1 and 32. As a comparative example, a similar revetment model was manufactured using a revetment block with the same shape but without water guide holes 7, 7..., and the reflectance obtained by conducting a similar experiment is shown in lines 33 and 34 in Fig. 3. show.

The experimental results show that the reflectance varies in various ways depending on the wave height and wave period, but under the same conditions, the examples of the present invention always show a lower reflectance than the comparative examples.

FIG. 4 shows that in the above-mentioned model, in order to investigate the influence of waves below the water surface, two types of upright blocks 13 were used, one with wave-dissipating holes and one without.
And as in the case of Fig. 3, the seawall blocks 1A to 1
Four combinations were made using N with water guide holes 7, 7... and those without.
For each, place the water surface at the mean water surface MSL,
Waves with a wave height of 1 m were applied. here,
Lines 41 and 42 show the case where a revetment block having water guide holes 7, 7... is used, and lines 43 and 44
shows the case where a revetment block without water introduction holes 7, 7... is used. Moreover, lines 41 and 43 show the case where the upright block 13 with wave-dissipating holes is used,
Lines 42 and 44 represent the upright block 13 without wave-dissipating holes.
Shows the case when used.

According to this experiment, when using a revetment block with water guide holes and when using an upright block with wave dissipating holes, the effect of reducing wave reflection was recognized. The mitigation effect was found to be greater than that of the upright blocks with wave-absorbing holes.

Figure 5 shows the relationship between the wave height and the overtopping of the wave over the top of the seawall. In the experiment, a 1/15 scale model was used, the water surface was placed at the average water level MSL, and when all the seawall blocks 1A to 1N had no water introduction holes 7, 7... (line 51), the water surface was approximately 1 m above the water surface. Block 1A below the position corresponding to
When using a block with water guide holes 7, 7, etc. in ~1F, and using a block with no water guide holes in blocks 1G to 1N above it (line 52), and conversely, if water guide holes are used in blocks 1G to 1N Testing was carried out by changing the wave height for each of the following three cases: using a block with holes 7, 7... and a block with no water guide holes in blocks 1A to 1F (line 53).

In the wave height coefficient (h/H) on the horizontal axis in Fig. 5,
h is the height (cm) from the water surface to the top of the seawall,
H is the wave height (cm). Overtopping coefficient (Q/√
2gH ³ ), Q is the amount of overtopping water per second per 1 cm of the normal line on the model (cm ³ /sec·cm), and g is the gravitational acceleration (cm/sec ² ).

As is clear from Figure 5, the overtopping water volume is
When the wave height H is lower than the height h of the seawall, it is almost zero, but when it exceeds the height h of the seawall, it increases rapidly.
The amount of overtopping water at that time is maximum when the entire seawall is constructed with blocks without water guide holes (line 51), and when blocks with water guide holes are used only in the lower half (line 5).
2) is the next most common, followed by the case where a block with water guide holes is used only in the upper half (line 53). In addition,
Although no experiments have been conducted, it is clear that the amount of overtopping water can be further reduced if the entire seawall is constructed of blocks with water guide holes.

Furthermore, when the wave is lower than the top of the seawall, the wave runs up to a position higher than the wave crest on the seawall surface, and the height of this run-up is related to the above-mentioned amount of overtopping water. Therefore, a seawall built with blocks with water guide holes has a lower wave run-up than a seawall built with blocks without water guide holes.

FIG. 6 shows an improved version of the revetment block according to the invention. The revetment block 61, like the revetment block shown in FIG. , and a plurality of water introduction holes 7, 7... In addition, a tenon 62 is provided on the lower surface of the front part, a mortise groove 63 is provided on the upper surface of the rear part 3, and an inclined surface 64 with a slope of 1/3 is provided on the lower surface of the rear part 3.
is doing.

FIG. 7 shows a seawall constructed using the seawall block 61 shown in FIG. Upper block 61B
The tenon 62 is the mortise groove 6 of the lower block 61A.
3, it is possible to prevent misalignment between the seawall blocks. In addition, the sloped surface 64 on the rear lower surface is connected to the seawall blocks 61A and 61B.
When stacked in stages, they are lined up on the same plane with a slope of 1/3, making it easy to create the stone and gravel layer 65 behind.

<Background of the Invention> As described above, when the seawall block according to the present invention is used, it is possible to build a stepped seawall that allows people to easily approach the water's edge, and the seawall suppresses incoming waves from running upstream. Therefore, the height of the seawall can be kept to the same level as the hinterland, and there is less wave reflection. In addition, it suppresses the splashing that occurs on the front of each block, and prevents water from forming on the top surface.
The risk of slipping can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a plan view, front view, and vertical sectional view of a revetment block according to the present invention, Fig. 2 is a sectional view of a revetment constructed using the revetment block shown in Fig. 1, and Figs. 3 and 4 are Figure 2 is a wave reflection characteristic diagram of the seawall shown in Figure 2 and the comparative example, Figure 5 is a wave overtopping characteristic diagram of the seawall constructed using various types of seawall blocks as shown in Figure 2, and Figure 6 is a wave reflection characteristic diagram of another embodiment of the present invention. FIG. 7 is a partial sectional view of a seawall constructed from the seawall blocks shown in FIG. 6. 2...front part, 3...rear part, 4...front upper surface, 5...recess, 6...front end surface, 7...water guide hole.

Claims (1)

[Claims] 1 The upper surface of the front part has a gentle downward slope toward the front, and has a recess in a portion adjacent to the rear of the upper surface of the front part, and a plurality of recesses are formed from the front end face having an inclination of an opposite slope toward the recess. A wave-dissipating stair revetment block characterized by having water guide holes.